linux-kernel - Re: [PATCH 3/5] mm: compaction: refactor __compaction

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20230602144942.GC161817@cmpxchg.org>
Date:   Fri, 2 Jun 2023 10:49:42 -0400
From:   Johannes Weiner <hannes@...xchg.org>
To:     Vlastimil Babka <vbabka@...e.cz>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Michal Hocko <mhocko@...e.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, kernel-team@...com
Subject: Re: [PATCH 3/5] mm: compaction: refactor __compaction_suitable()

On Mon, May 29, 2023 at 07:11:35PM +0200, Vlastimil Babka wrote:
> On 5/19/23 14:39, Johannes Weiner wrote:
> > __compaction_suitable() is supposed to check for available migration
> > targets. However, it also checks whether the operation was requested
> > via /proc/sys/vm/compact_memory, and whether the original allocation
> > request can already succeed. These don't apply to all callsites.
> > 
> > Move the checks out to the callers, so that later patches can deal
> > with them one by one. No functional change intended.
> > 
> > Signed-off-by: Johannes Weiner <hannes@...xchg.org>
> 
> Acked-by: Vlastimil Babka <vbabka@...e.cz>
> 
> Note comment on compaction_suitable() still mentions COMPACT_SUCCESS, that
> is no longer possible, so delete that line?

Good catch, let's remove it.

> Also on closer look, both compaction_suitable() and __compaction_suitable()
> could now simply return bool. The callers use it that way anyway. There
> would just be some extra fiddling internally aroud the tracepoint.

Also a great idea. This will raise conflicts in later changes, so I'll
send a new patch to go on top of the stack.

Andrew, can you please fold this? Thanks!

---
>From abaf21e8dc2a3ed2aa181e0c89403807e5cea67d Mon Sep 17 00:00:00 2001
From: Johannes Weiner <hannes@...xchg.org>
Date: Fri, 2 Jun 2023 10:13:15 -0400
Subject: [PATCH] mm: compaction: refactor __compaction_suitable() fix

Vlastimil points out the function comment is stale now. Update it.

Signed-off-by: Johannes Weiner <hannes@...xchg.org>
---
 mm/compaction.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/mm/compaction.c b/mm/compaction.c
index 8f61cfa87c49..0503cb59c1cb 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -2238,7 +2238,6 @@ static enum compact_result __compaction_suitable(struct zone *zone, int order,
  * compaction_suitable: Is this suitable to run compaction on this zone now?
  * Returns
  *   COMPACT_SKIPPED  - If there are too few free pages for compaction
- *   COMPACT_SUCCESS  - If the allocation would succeed without compaction
  *   COMPACT_CONTINUE - If compaction should run now
  */
 enum compact_result compaction_suitable(struct zone *zone, int order,
-- 
2.40.1